/*
 * @Descripttion: 图片懒加载
 * @version: 
 * @Author: 某人
 * @Date: 2021-04-29 15:29:26
 */
let imgList = [...document.querySelectorAll('img')]
let length = imgList.length
const imgLazyLoad = ((function() {
  let count = 0
  return function () {
    let deleteIndexList = []
    imgList.forEach((img, index) => {
      let rect = img.getBoundingClientRect()
      if (rect.top < window.innerHeight) {
        img.src = img.dataset.src
        deleteIndexList.push(index)
        count++
        if (count === length) {
          document.removeEventListener('scroll', imgLazyLoad)
        }
      }
    })
    imgList = imgList.filter((img, index) => !deleteIndexList.includes(index))
  }
} ()))
// 这里最好加上防抖处理
document.addEventListener('scroll', imgLazyLoad)